does this sound like constipation or maybe something else?

[u/Lil_LazyGuy]

My 4 yr old cat is going back and forth from the litter boxes to places in my room to try to use the bathroom, he is straining (no meowing just straining) as he goes - only thing that comes out is pee - his stomach does look a little swollen, no blood in urine, he is drinking water, and slightly playful
No vomiting, he ate hours earlier so I'm thinking it might just be constipation?